Polyurethane compositions for golf balls

Abstract

Polyurethane and polyurea compositions for golf balls with improved stability of the curative blend, wherein the curative blend includes a pigment, a curing agent, and a compatible freezing point depressing agent so that the curative blend has a lower freezing point than the curing agent by itself and the blend does not lose pigment dispersion upon solidification and subsequent thawing.

1. A method of forming a golf ball comprising the steps of:
 providing a curative blend formed from at least one curing agent, at least one compatible freezing point depressing agent, and at least one grind vehicle comprising a pigment; 
 forming a composition comprising:
 a prepolymer formed from the reaction product of an isocyanate and a polyol or polyamine; and 
 the curative blend; and 
 
 forming at least a portion of the golf ball from the composition. 
 
     
     
       2. The method of  claim 1 , wherein the step of forming at least a portion of the golf ball comprises providing a core and forming a cover from the composition disposed about the core. 
     
     
       3. The method of  claim 1 , wherein the step of providing a curative blend further comprises mixing a saturated curing agent, at least one compatible saturated freezing point depressing agent, and at least one grind vehicle comprising a pigment to form the curative blend. 
     
     
       4. The method of  claim 1 , wherein the step of providing a curative blend comprises selecting at least one curing agent having a first freezing point, and wherein the curative blend has a second freezing point that is less than the first freezing point by about 5° F. or greater. 
     
     
       5. The method of  claim 4 , wherein the second freezing point is less than the first freezing point by about 15° F. or greater. 
     
     
       6. The method of  claim 1 , wherein the step of providing a curative blend comprises selecting a freezing point depressing agent having a freezing point from about −10° F. to about −100° F. 
     
     
       7. The method of  claim 1 , wherein the step of providing a curative blend comprises selecting a freezing point depressing agent comprising hydroxy-terminated freezing point depressing agents selected from the group consisting of 1,3-propanediol, 2-methyl-1,3-propanediol, 2-methyl-1,4-butanediol, 1,2-butanediol, 1,3-butanediol, ethylene glycol, diethylene glycol, 1,5-pentanediol, polytetramethylene glycol, propylene glycol, or mixtures there of. 
     
     
       8. A method of forming a golf ball comprising:
 providing a core; 
 forming a composition comprising:
 a saturated prepolymer formed from the reaction product of a saturated isocyanate and a saturated polyol, saturated polyamine, or a mixture thereof; and 
 a saturated curative blend formed from at least one saturated curing agent, at least one saturated compatible freezing point depressing agent, and a grind vehicle comprising a pigment; and 
 
 forming a cover from the composition about the core. 
 
     
     
       9. The method of  claim 8 , wherein the composition has a pigment dispersion of about 5 or greater on the Hegman scale. 
     
     
       10. The method of  claim 8 , wherein the step of forming the cover comprises forming a cover from the composition having a thickness of about 0.02 inches to about 0.035 inches. 
     
     
       11. The method of  claim 8 , wherein the at least one saturated freezing point depressing agent has a freezing point of about −10° F. to about −120° F. 
     
     
       12. The method of  claim 8 , wherein the at least one saturated curing agent has a first freezing point and the saturated curative blend has a second freezing point, and wherein the second freezing point is less than the first freezing point by about 10° F. or greater. 
     
     
       13. A method of making a golf ball comprising the steps of:
 forming a solvent-free pigment dispersion comprising at least one pigment contained in a grind vehicle, a curing agent, and a freezing point depressing agent, wherein the pigment dispersion has a Hegman scale value of greater than about 1 after a freeze/thaw cycle without redispersing the pigment, and wherein the freezing point depressing agent has a freezing point of about −10° F. to about −120° F.; and 
 forming at least one of a cover or core from the solvent-free pigment dispersion. 
 
     
     
       14. The method of  claim 13 , wherein the step of forming a solvent-free dispersion comprises selecting a curing agent having a first freezing point and selecting a freezing point depressing agent having a second freezing point less than the first freezing point. 
     
     
       15. The method of  claim 14 , wherein the step of selecting a freezing point depressing agent comprises selecting the freezing point depressing agent from the group consisting of 1,3-propanediol, 2-methyl-1,3-propanediol, 2-methyl-1,4-butanediol, 1,2-butanediol, 1,3-butanediol, ethylene glycol, diethylene glycol, 1,5-pentanediol, polytetramethylene glycol, propylene glycol, and mixtures thereof. 
     
     
       16. The method golf ball of  claim 13 , wherein the solvent-free pigment dispersion measures about 5.0 or greater on the Hegman scale. 
     
     
       17. The method of  claim 13 , wherein the step of forming a solvent-free dispersion further comprises mixing the solvent-free dispersion with a prepolymer formed from the reaction product of an isocyanate and a polyol or a polyamine.